In general, as display devices, for example, liquid crystal display devices and organic electroluminescent display devices are known. These display devices are provided in portable devices such as smartphones, PDAs or tablet computers.
When the load on the display panel is changed, a booster circuit or a regulator for driving the liquid crystal cannot follow the change. In this manner, ripples (noise) are produced in the source voltage. The ripples may have various detrimental effects on the liquid crystal display device.